Purification of DNA for the transfection of a Spodoptera frugiperda cell line

Spodoptera frugiperda (Sf-9) cells have been widely used in baculovirus expression systems, transient gene expression studies and transgenic cell lines. These applications commonly require the transfection of bacterial plasmid DNA. One of the most reliable methods of preparing transfection-quality plasmid DNA is cesium chloride (CsCl) density gradient centrifugation. However, the traditional CsCl DNA purification is a long and laborious process. We have made a series of modifications to the traditional method that makes it faster, safer and easier. In the current study we demonstrate that DNA prepared by our modified CsCl method was also better for the transfection of Sf-9 cells than DNA prepared by the traditional CsCl method.     

长QT间期扭转型室性心动过速发病机制探讨

狗静脉注射氯化铯(CsCl)所致的多形性室性心动过速(室速)基本符合长QT间期扭转型室速(TdP)的特点。右室心内膜单相动作电位(MAP)记录表明,CsCl可诱发早期后除极电位(EAD),TdP发作与EAD密切相关,硫酸镁(MgSO_4)可使EAD消失,TdP也获控制,提示TdP为EAD触发活性所致。Cs~ 为细胞膜K~ 通道阻滞剂,延长复极时间,增加内向Na~ /Ca~(2 )流,由此产生EAD,而Mg~(2 )为细胞膜K~ 通道激动剂,因此,Mg~(2 )对Cs~ 具对抗作用。     

Assessment of the transfer of Cs in three types of vegetables consumed in Hong Kong

A dynamic food chain model has been built for the modeling of the transfer of ¹³⁷Cs in three types of vegetables consumed in Hong Kong, namely, white flowering cabbage (Brassica chinensis), head lettuce (Lactuca sativa) and celery (Apium graveolens). Some parameters have been estimated from the experimental data obtained in this work. The experimental data include the transfer factors of ¹³⁷Cs from soil to the different vegetable species which are determined through high resolution gamma spectrometry, maximum crop biomasses for the vegetable species, the dry-to-fresh ratios for the vegetable species, the bulk density of soil layers and the average concentration of ¹³⁷Cs in air. The derived parameters include the deposition rate and the root uptake rate, information for tillage, the logistic growth model and radionuclide concentrations in vegetables. The dynamic food chain model is solved by the Birchall–James algorithm to give the ¹³⁷Cs concentration in subsurface soil, from the 0.1–25 cm soil layer, and the ¹³⁷Cs concentration in harvested and unwashed vegetables. As validation of the model and parameters, the concentrations obtained experimentally and from the model are compared and are found to be in good agreement.     

信号核素134Cs诱发体细胞和生殖细胞畸变效应比较研究

对１３４Ｃｓ诱发体细胞和生殖细胞的畸变效应进行了比较研究。方法观察内污染不同放射性活度１３４Ｃｓ时诱发同体骨髓细胞和精原细胞染色体畸变的量效关系，以及同一放射性活度１３４Ｃｓ作用不同时间诱发上述两种细胞的染色体畸变产额。结果研究发现，１３４Ｃｓ内照射诱发的骨髓细胞染色体畸变产额显著高于精原细胞，而其诱发的染色体畸变类型均以染色单体型畸变为主。结论由不同放射性活度１３４Ｃｓ所诱发的染色体畸变产额而言，骨髓细胞要比精原细胞高出１．５～５倍。     

碘化铯非晶硅平板探测器的原理及应用

通过介绍碘化铯非晶硅平板探测器的材料特性、工作原理和临床应用等特点,表明了该项技术的优缺点、发展方向及在数字化摄影系统中的重要地位。     

Vitamin D metabolism impairment in the rat’s offspring following maternal exposure to <Superscript>137</Superscript>cesium

Previous works clearly showed that chronic contamination by ¹³⁷cesium alters vitamin D metabolism. Since children are known to be a high-risk group for vitamin D metabolism disorders, effects of ¹³⁷Cs on vitamin D biosynthetic pathway were investigated in newborn rats. The experiments were performed in 21-day-old male offspring of dams exposed to ¹³⁷Cs in their drinking water at a dose of 6,500 Bq/l (150 Bq/rat/day) during the lactation period. Significant modifications of blood calcium (−7%, P < 0.05), phosphate (+80%, P < 0.01) and osteocalcin (−25%, P < 0.05) levels were observed in contaminated offspring, associated with an increase of blood vitamin D₃ (+25%, P < 0.01). Besides, decreased expression levels of cyp2r1 and cyp27b1 (−26 and −39%, respectively, P < 0.01) were measured in liver and kidney suggesting a physiological adaptation in response to the rise in vitamin D level. Expressions of vdr, ecac1, cabp-d28k, ecac2 and cabp-9k involved in renal and intestinal calcium transport were unaffected. Altogether, these data show that early exposure to post-accidental doses of ¹³⁷Cs induces the alteration of vitamin D metabolism, associated with a dysregulation of mineral homeostasis.     

Cesium chloride-induced torsades de pointes

The chloride salt of cesium, a group 1A element, is gaining popularity as an alternative treatment of advanced cancers. Cesium chloride has primarily been used in cardiovascular research for arrhythmogenesis in animals because of its potassium-blocking effects. The present report describes a 45-year-old woman with metastatic breast cancer who experienced repeated episodes of torsades de pointes polymorphic ventricular tachycardia after several months of oral cesium therapy. There was a clear temporal relationship between cesium ingestion and the arrhythmia, which later resolved following discontinuation of cesium therapy. Serial cesium plasma and whole blood levels were measured over the ensuing six months and pharmacokinetic analysis was performed.     

Cesium chloride protects cerebellar granule neurons from apoptosis induced by low potassium

Neuronal apoptosis plays a critical role in the pathogenesis of neurodegenerative disorders, and neuroprotective agents targeting apoptotic signaling could have therapeutic use. Here we report that cesium chloride, an alternative medicine in treating radiological poison and cancer, has neuroprotective actions. Serum and potassium deprivation induced cerebellar granule neurons to undergo apoptosis, which correlated with the activation of caspase-3. Cesium prevented both the activation of caspase-3 and neuronal apoptosis in a dose-dependent manner. Cesium at 8 mM increased the survival of neurons from 45 +/- 3% to 91 +/- 5% of control. Cesium's neuroprotection was not mediated by PI3/Akt or MAPK signaling pathways, since it was unable to activate either Akt or MAPK by phosphorylation. In addition, specific inhibitors of PI3 kinase and MAP kinase did not block cesium's neuroprotective effects. On the other hand, cesium inactivated GSK3beta by phosphorylation of serine-9 and GSK3beta-specific inhibitor SB415286 prevented neuronal apoptosis. These data indicate that cesium's neuroprotection is likely via inactivating GSK3beta. Furthermore, cesium also prevented H(2)O(2)-induced neuronal death (increased the survival of neurons from 72 +/- 4% to 89 +/- 3% of control). Given its relative safety and good penetration of the brain blood barrier, our findings support the potential therapeutic use of cesium in neurodegenerative diseases.     

Alkali metal cations: effects on aggression and adrenal enzymes

Alkali metal cations (lithium, sodium, potassium, rubidium and cesium) were given to rats on a chronic large dose schedule. Lithium depressed shock induced fighting, while potassium and rubidium facilitated this aggression. After chronic high doses of the alkali cations, all groups except the sodium treated group showed an elevation of the adrenal enzymes, tyrosine hydroxylase and phenylethanolamine-N-methyl transferase (PNMT).